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Achieving shallow DOF


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#1 Malik Sajid

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Posted 06 May 2008 - 07:32 AM

Ok here is a pretty question that was confusing me since quite a time.

how we can achieve shallow DOF with simple dv cams, say XL1, or the one that i am using sony dsr 250? Does DOF depend on lens, or the quality of camera? uh sound stupid.


i hope u got me.
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#2 Freya Black

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Posted 06 May 2008 - 11:27 AM

Ok here is a pretty question that was confusing me since quite a time.

how we can achieve shallow DOF with simple dv cams, say XL1, or the one that i am using sony dsr 250? Does DOF depend on lens, or the quality of camera? uh sound stupid.


i hope u got me.


It's nothing to do with the lens per se, however it is to do with the apeture of the lens. f2.0 will have shallower depth of field than f16. That's true of any lens tho! :)

It's also to do with the size of the ccd in the camera. Cameras with a bigger ccd will have a shallower depth of field. It's like with film in a movie camera, the smaller the filmstock, the greater the depth of field.

love

Freya
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#3 John Holland

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Posted 06 May 2008 - 11:33 AM

And if you shoot at a longer focal length on you zoom so the depth of field becomes less .
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#4 Brian Drysdale

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Posted 06 May 2008 - 11:38 AM

Ok here is a pretty question that was confusing me since quite a time.

how we can achieve shallow DOF with simple dv cams, say XL1, or the one that i am using sony dsr 250? Does DOF depend on lens, or the quality of camera? uh sound stupid.


i hope u got me.


The common approach is to put a 35mm DOF adapter on. Basically this uses a 35mm sized ground glass (this can be spinning to reduce the texture), which is in some designed is filmed using the camera's own lens. Of course, the ground glass adds diffusion.

There are a number of manufacturers.

http://en.wikipedia....f-field_adapter
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#5 Michael Nash

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Posted 06 May 2008 - 12:08 PM

http://en.wikipedia..../Depth_of_field

http://www.cambridge...th-of-field.htm

http://www.cs.mtu.ed...h-of-field.html

Depth of field is determined by three things: aperture, focal length, and distance to subject. Wider apertures, longer focal lengths, and closer distances from lens to subject create the shallowest depth of field.

The smaller the size of the sensor or film, the shorter the focal length you need to maintain the same field of view. With 1/3" chip cameras you end up with focal lengths so short that wide apertures and close distances often aren't enough to create shallow depth of field.
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#6 Allen Achterberg

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Posted 06 May 2008 - 03:18 PM

And if you shoot at a longer focal length on you zoom so the depth of field becomes less .


not actually true.

matching the field of view with two different lens lengths and a common stop will yield the exact same depth of field. The longer lens will compress the distance however, making the DOF fall off appear much quicker.
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#7 Malik Sajid

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Posted 07 May 2008 - 07:14 AM

not actually true.

matching the field of view with two different lens lengths and a common stop will yield the exact same depth of field. The longer lens will compress the distance however, making the DOF fall off appear much quicker.


And longer lens means a wider lens like 25 or 18 mm???
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#8 Freya Black

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Posted 07 May 2008 - 07:43 AM

And longer lens means a wider lens like 25 or 18 mm???


Longer usually means more telephoto! Like 100mm :)

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#9 Malik Sajid

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Posted 07 May 2008 - 09:19 AM

arrright


so how do we control the light say we open the aperture wide open say f2.8 or may be less.

Say shooting interview at outdoors, and opening aperture wide may increase the amount of light enterting. We use nets and accessories like that?


Working with Sony 250p, with lens that can go say from 18 to 125mm, how to play with DOF?

Do I really need some fized lens?
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#10 Michael Nash

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Posted 07 May 2008 - 02:40 PM

Say shooting interview at outdoors, and opening aperture wide may increase the amount of light enterting. We use nets and accessories like that?



You use Neutral Density filters on the camera to control the amount of light coming into the lens, so that you can shoot at a desired aperture.


Working with Sony 250p, with lens that can go say from 18 to 125mm, how to play with DOF?


You have all the answers here already. Long lens, wide aperture, close distance to subject; OR use a relay-lens adapter system with 35mm lenses.
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#11 Malik Sajid

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Posted 08 May 2008 - 10:50 AM

yah, right

thanks a lot everyone


isn't it hard to get good results with dv cams?
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#12 Adam Nottingham

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Posted 12 May 2008 - 10:38 PM

Lower end DV performance seems to plateau somewhat early, however you can definitely obtain "good" results in the depth of field realm. I have even gotten decent shallow DOF shots on the XL1s little invalid brother the GL2.
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#13 Sander van de kerkhof

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Posted 14 May 2008 - 02:42 PM

The way to go is to use the camera on full manual mode, set your F stop at 2.0 (as i recall this is max open for the dsr250).
As said before you can use the ND1 or ND2 filter to control your light to stay at this aperture...

And also experiment with different focal lengths, if you zoom in nearing the end of the lens your background will look more out of focus (don't go to the very end of your lens, you lose allot of light there).

also experiment with the distance of your subject to your lens and distance of your subject in relation to the background.
do some tests this will help you to understand DOF and how to use it.

Sander,
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#14 Malik Sajid

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Posted 15 May 2008 - 03:48 AM

Sender! thats a good one

thanks a lot bro
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